Oil burner



y 1956 c. s. BRELSFORD 2,746,531

' OIL BURNER Filed April 6, 1951 v 2 Sheets-Sheet l 15'\ Fig. 1

Zmventor CHARLES G. BRELSFORD WM/M Z Gttornega May 2, W56 c. s. RELSFQRD OIL BURNER 2 Sheets-Sheet 2 Filed April 6, 1951 1 Claim. Cl. 158-76) This invention relates to oil burners for heating purposes and the like, and more particularly to oil burners ,of the low pressure type which incorporate an air pump supplying primary air to the nozzle in the combustion head for dischargewith the atomized oil for combustion with the secondary air supplied to the combustion head by a secondary air source blower such as a fan or centrifugal blower wheel.

The invention has special application to the air pump in an oil burner of this character and to the supply system for air to the suction side of the air pump. In such oil burners as previously constructed wherein the air intake to the air pump is at atmospheric pressure, the suction tends to produce an objectionable whistling noise, and muffling means are usually provided to reduce this noise. Furthermore, some of the devices employed for this muffling action have been relatively complicated in structure,

nited States Patent 2,746,531 Patented May 22, 1956 Fig. 4 is a detail view of the adapter which supports the rearward end of the nozzle tube;

Fig. 5 is a sectional view of theadapter and associate fitting for the oil and air tubes, the view being in section on the line 5-5 of Fig. 9; i

Fig. 6 is a view of the adapter taken in section on the line 66 of Fig. 4; a 7

. Figs. 7'and 8 are detail views of the two ends of the adapter fitting; t

Fig. 9 is a detail view partly in elevation andpartly in section of the adapter and fitting; and

Fig. 10 is a sectional view showing the atomizing air pump, the view being in section on the line 10-10 of Fig. 2. t

Referring to the drawings, which illustrate a preferred embodiment of the invenion, Figs. 1 and 2 show the general construction of an oil burner of the low pressure type involving special configuration of the pump housing as well as an involved arrangement of interfitting parts for extending the path of travel of the incoming air from outside the housing to the pump chamber.

It is accordingly one of the principal objects of the present invention to provide an oil burner of the above type wherein the air is supplied to the suction side-of the air pump substantially without accompanying noise and without requiring complicated muflling devices, and more particularly to provide such an oil burner wherein the static pressure produced at the cutoff point of the secondary air blower is employed to break the suction pressure at the point of intake to the air pump.

It is also an object of the invention to provide an oil burner of the above type wherein the intake to the air pump is directly c'onnectedf'with the discharge side of the. secondary air blower to supply air under pressure to the. air pump while at the same time utilizing the large mass of the blower housing and blast tube assembly as a "muffler for the noise which might otherwise be created at the'suction side of the air pump. i V

A further object of the invention is to provide a simple and economical device for incorporation in an oil burner of the above character to intercept a portion of the secondary air discharged from the blower at a position between the blower discharge point and the nozzle of the burner, and to conduct this intercepted air directly to the suction side of the primary air pump.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claim.

In the drawings Fig. 1 is a view in side elevation, partly broken away in vertical section, showing an oil burner in accordance withthe invention;

Fig. 2 is a rear elevational view of the oil burner with portions broken away;

Fig. 3 is a diagrammatic view showing the path of flow of the oil and the primary and secondary air in the operation of the oil burner;

adapted for conversion use in domestic installations. This burner is shown as including a main housing 15 provided 7 with a pedestal type supporting base 16 including an upper portion 20 which forms a blower chamber in which is mounted the blower'wheel 22 for supplying secondary air to the combustion head24 at the outer end of the blast tube 25, which is secured within the open portion 26 of the housing by attaching screws 27.- The pump assembly for supplying oil at a metered rate to the combustion head is indicated generally at 28, and it is shown in detail. in the copending application of Getz and Hedges, Serial No. 200,232, filed December 11, 1950, and assigned to the same assignee as this application. It includes the housing 30 of an atomizing air pump shown in detail in Fig, 10, and the motor 31 for driving this pump assembly is mounted to the opposite side of the housing.

Thenozzle 33 is mounted within the combustion head 24 on the outer end of the primary air tube34, which encloses the oil tube 35 and is supported within the blast tube 25 by means of a multi-armed bracket 36 of generally Y-shape. The forward end of this bracket is secured to the air cone 37 provided with swirl blades 38 for imparting a swirling motion to the secondary .air traveling through the blast tube, and the bracket 36 also supports the electrodes 40 for igniting the atomized supply of oil and primary air discharged from the nozzle 33. The electrode cables 41 are supported on the air tube 34 by means of a spacer 42 and lead fromthe ignition transformer 44 mountedon the housing 30- below thedrive motor 31. Symmetricallymounted on the other side of the housing from the transformer is a primary combustion control unit enclosed within a removable cover-45 and provided with the usual reset button 46 for resetting the primary combustion control in case of a safety shutdown of the burner unit.

with an air inlet passage 52 and an oil inlet passage 53 which are relatively diverging as shown in Fig. 5. Another passage 55 of right angled shape is formed in the adapter as shown in Figs. 4 and 6 and is provided at its ends with ports 56 and 57.. The rearward end of the oil tube 35 is threaded into a hollow plug 60 having a sliding fit in the bore 51 and located between the air and oil passages 52 and 53. The plug 60 is formed with a circumferential groove for receiving a ceiling ring 61 preventing communication between the passages 52 and 53 around the outside of the plug, thus causing the oil from passage 53 toflow directly through oil tube 35 while the air from passage 52 flows outwardly of tube 35 through the annular passageway remaining within air tube 34. The forward end of the oil tube 35 supports a nozzle jet, as shown in the above noted application Serial No. 200,232, and a spring 62 is mounted within the adapter 50 and bears and nozzle jet forwardly into the desired'fitted relation of the forward end of the jet in the nozzle. 1

The adapter is bolted at 63 to a boss portion 64 of the housing .with its threaded end portion projecting through the wall of the housing to receive the fitting 65 and. fitting nut 66. The fitting65 has three passages 70, 7.2 and 73 extending'therethrough and arranged to match the port 57 and the outer ends of the passages 52 and 53 respectively on the adapter 55. In order to align the fitting and adapter, the mating ends thereof are drilled at 75 and 76- to receive a locating pin or dowel, and the ends of the passages 72 and 73 are counterbored as shown to receive sealing rings as indicated at 77 inFig. 5. v The outer ends of these passages 70, 72 and 73 are also counterbored to receive the ends of three tubes 80, 82 and 83,

which are permanently secured to the fitting as by brazing. The tube 83 is connected at 85 with the discharge side of the oil metering pump assembly, and the tubes 80 and 82 are connected respectively with the suction and discharge sides of the atomizing air pump as shown in detail in Fig. 10.

Referring to Fig. 10, the ring shaped housing 30 of the air pump encloses a circular chamber in which the rotor-91 rotates eccentrically with thedrive shaft 92 driven by motor 31; Multiple vanes or blades 93 are carried loosely in slots 94 in the periphery of the hub of rotor 91 and are maintained'in' contact with the wall of the chamber 90 by centrifugal force. The passage 95 for air to chamber 90 is provided at its outer end with an elbow connection'96 whichis in turn directly connected at 97 to the end=of the tube 80. I

The discharge port 99 from chamber 90 is provided with a needle valve 100 for regulating the discharge pressure to the fitting 101 which is directly connected with the tube 82. The'valve 100'controlsa bypass passage 105 which is connected by a groove (not shown) in the face of the pump housing 3-0 with the suction side of the chamber 90. The'groove 106 in theopposite surface of the pump housing matches a passage in the'face of the oil pump assembly to transmit oil from the oil pump assembly of the chamber 90 to lubricate-the rotor assembly as described in the above noted application Serial No. 200,232. I Grooves 107'and 108 are provided in the suction and discharge sides with chamber 90 to even out pulsations of the suction and discharge air which may result from the multivaned rotor construction in operation.

,As shown particularly in Figs. 2 and 3, when the adapter 50is mounted within the housing portion 26, it extends into the path' of the secondary air discharged from the blower 22, and the port 56 of the passage 55 directly faces the flow of secondarytair. Since the rotor 91 is on the same shaft as theblower Wheel and istherefore in operation at the same time as the blower wheel to create suction on the inlet passage 95, this suction will be effective at the port 56 to draw in the intercepted portion of the secondary air flow and to supply it directly to the air pump. Thus since the effective suction point of the air pump is located at the port 56, any tendency towards whistling which might otherwise be apparent Will be effectively mufiiled by the large mass of the main blower housing and blast tube assembly, and no separate muffling means are required. At thersame time, with the suction point of the air pump thuslocated between the blower discharge point and the nozzle of the burner, the total pressure discharged by the blower is applied to the suction opening of the air pump for more effective operation of the burner as a Whole.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claim.

What is claimed is:

In an oil burner comprising a blower housing including a blast tube extending therefrom. with said blast tube having a combustion head at the forward end thereof, the combination of a primary air tube Within said blast tube, an oil tube within said air tube, a nozzle at the forward ends of said air and oil tubes for discharging an atomized spray of oil and primary air therefrom, a blower within said housing for supplying secondary air through said blast tube to said combustion head, an adapter connected to the rearward ends of said air and oil tubes, means securing said adapter within said housing on the discharge side of said blower to support said air and oil tubes within said blast tube, a primary air passage in said adapter connected with said air tube, an oil passage in said adapter connected with said oil tube, a primary air pump, an oil pump, means connecting the discharge sides of said air pump and said oil pump with said air passage and said oil passage respectively, said adapter. having a third passage therein provided with a port in the rearward side of said adapter at a position located within the path of the secondary air discharged by said blower, and a conduit connecting said third passage in said adapter with the suction side of said air pump to supply air to the suction side of said air pump at the total discharge pressure of said blower.

References Cited in the file of this patent UNITED STATES PATENTS 1,379,178 Good May 24, 1921 1,379,179 Good May 24, 1921 1,394,894 Good Oct. 25, 1921 2,120,387 Bargeboer June 14, 1938 2,452,779 McCollum Nov. 2, 1948 

